#pragma once
namespace LI
{
	template<class T>
	struct list_node
	{
		T _data;
		list_node<T>* _next;
		list_node<T>* _prev;

		list_node(const T& x = T())
			:_data(x)
			,_next(nullptr)
			,_prev(nullptr)
		{}
	};

	template<class T,class Ref,class Ptr>
	struct _list_iterator
	{
		typedef list_node<T> Node;
		typedef _list_iterator<T, Ref, Ptr> Self;
		Node* _node;
		
		_list_iterator(Node* node)
			:_node(node)
		{ }

		Ref operator*()
		{
			return _node->_data;
		}

		Ptr operator->()
		{
			return &_node->_data;
		}

		Self& operator++()
		{
			_node = _node->_next;
			return *this;
		}
		Self operator++(int)
		{
			Self tmp(*this);
			_node = _node->_next;
			return tmp;
		}

		Self& operator--()
		{
			_node = _node->_prev;
			return *this;
		}

		Self operator--(int)
		{
			Self tmp(*this);
			_node = _node->_prev;
			return tmp;
		}

		bool operator!=(const Self& it) const
		{
			return _node != it._node;
		}

		bool operator==(const Self& it) const
		{
			return _node == it._node;
		}

	};
	template<class T>
	class list
	{
		typedef list_node<T> Node;
	public:
		typedef_list_iterator<T, T&, T*> iterator;
		typedef_list_iterator<T, const T&, const T*> const_iterator;

		iterator begin()
		{
			return iterator(_head->next);
		}

		iterator end()
		{
			return iterator(_head);
		}

		const_iterator begin() const
		{
			return const_iterator(_head->_next);
		}

		const_iterator end() const
		{
			return const_iterator(_head);
		}

		void empty_init()
		{
			_head = new Node;
			_head->_next = _head;
			_head->_prev = _head;
		}

		list()
		{
			empty_init();
		}

	};
}